Method of making color designs in gypsum sheets



Sept. 14, 1965 A. E. MURRAY METHOD OF MAKING COLOR DESIGNS IN GYPSUM SHEETS Filed Aug. 22, 1961 INVENTOR. ALAN E. MURRAY ATTORNEYS 3,236,527 METTI-EGB @if lll/MUN@ CULR DESIGNS IN GY'SUM SHEETS Alan 1E. Murray, 616 .Fairfield Ave., rldgeport, Conn. Filed Aug. 22., 1961, Ser. No. 133,220 S Claims. (Cl. 264-73) This application is a continuation-in-part of my earlier copending applications Serial No. 861,367, led December 22, 1959 and Serial No. 28,074, filed May 10, 1960 (both now abandoned), and other matters disclosed in such earlier cases are also being claimed in my copending application entitled Method of Forming Thin Resilient Shells, tiled of even date herewith.

This invention relates to a method of producing permanent color designs in thin gypsum sheets and to the products so prepared. The method may be employed to copy and duplicate a design from virtually any source, as a new art technique for original creative work and to cover interior room surfaces such as floors, walls and ceilings, with durable non-inflammable gypsum sheets having brilliantly colored designs and decorations.

Since the time of the early Roman Empire the technique of fresco paintings has been known to civilization. Basically, the fresco method involved painting the surface of a mortar made of slaked lime and `sand with pigment washes. The artist had to be painstakingly careful in preparing the mortar, in planning on what area he could cover with colors before the mortar dried, in applying his colors with uniformity and in accounting for the adverse etl'ect on appearance of colors of a constantly varying degree of dryness of the mortar as the work progressed. The entire process was slow, laborious, done day by day with freshly prepared mortar in predetermined patch areas which then had to be merged one with the other by touch-up to produce murals and other decorations of a large size. Today the fresco technique has largely fallen into disuse and undoubtedly the inherent technical difficulties of its execution, as well as its time consuming demands, are primarily responsible for this.

I have now discovered a method which makes it possible to incorporate color designs into a thin sheet of gypsum in a matter of minutes. In its essence the method comprises the steps of depositing water soluble or water dispersible coloring matter in substantially aqueous vehicles upon a suitable backing to form a design thereon, permitting the colors to dry, then causing the design to contact the surface of a thin layer of aqueous gypsum plaster slurry while the gypsum plaster is `in a physically impressionable form. slurry also must be controlled and strengthened, preferably With wet open mesh fabric material although other wet sheet materials may be employed. As the plaster particles contact the design the colors therein migrate into the slurry and when the gypsum plaster has hardened through recrystallization, .the colors are locked within the crystal lattice of the gypsum particles in the hard sheet. The final result is a completely stabilized color-fast design of virtually unlimited permanence and resistance .to deterioration.

My invention modernizes 'the ancient art of fresco painting in that it makes possible for the first time, fresco art effects in gypsum plaster, a material which was not known to the ancients and which, even if known, would have been incapable of being worked according to their techniques because of its rapid hardening. While the ancients `spend days and often weeks in producing their frescoes with slow drying mortars of slaked lime and sand, it is possible with the methods of my invention to form colorful fresco-like sheets of gypsum plaster in a matter of minutes. Thus, the invention may be used by The thin layer of gypsum plaster o United States Patent individuals in creating original art works or in industry on a mass production commercial basis.

One of the most remarkable features of my invention is the fidelity of detail with which a multi-color design is reproduced in the thin sheet `of gypsum. As used in the specifica-tion and claims, herein, the term design is intended to refer .to a preplanned arrangement of color in which the color appears in particular shapes and forms, which contrast with each other in a manner that is discernible when the design is Viewed. The arrangement may be highly ordered as in portraits, landscapes and other simulations of real objects or as in colored patterns in which one or more color motifs are presented in some repetitions manner. The arrangement may also be random as in modern abstractions where irregular splashes of color and like schemes are employed. Naturally, in order to arrange color in contrasting shapes and forms, at least .two different colors must be employed. Any combination of chromatic and achromatic colors may be used, including :the case where a single color, other than that of the gypsum plaster, is arranged in particular shapes and forms to contrast with the natural white color of the gypsum plaster to create a design.

With my method the `lines delineating the borders and differently colored areas of the design are faithfully preserved in the nal product. Delicate shades of color and even brush strokes are captured in the gypsum sheet being blurred or smeared. At this time I do not completely understand the reasons for this but I have observed certain important facts.

When the design is painted on a backing and then dried, it is completely washable since the colors that are employed are either water soluble or water dispersible. By completely washable I mean that a moist piece` of cloth `or paper wiped across the face of the design will either wash it away completely or cause the colors therein to smear so severely that the design is in effect destroyed. Yet, when layers of open mesh fabric material are placed over the design and the assembly then wetted with Water, there is no tendency toward smearing, blurring or other adverse effect in the colors `of the design. The water is applied liberally to the fabric material-design assembly and thoroughly spread with a brush or roller to make certain that the entire area of the design and the fabric layer is wetted. The fact that the colors do not change their relative positions under such thorough wetting indicates that the open mesh fabric material exerts some form of control, perhaps by breaking up and conning the hlm of water to within the closed perimeter of each individual mesh area in the material and thereby preventing any colors which are absorbed by the water within each perimeter from moving into adjacent perimeters. Whatever the actual explanation may be I have quite unexpectedly found that the important step of wetting the open mesh fabric material can bc readily carried out without impairing the appearance of the design either initially or in the final product.

After the wetting step is completed, an aqueous slurry of gypsum plaster is applied to the fabric material-design assembly. The consistency of this slurry should be quite loose and free flowing so that it can be readily spread over the entire design. As the slurry is applied an important interaction between the wet bers of the fabric material and the plaster particles apparently takes place. First of all, the plaster particles appear to be attracted by the water on the design surface and in the fibers of the fabric material and this is shown by an instantaneous lateral diffusion of the particles into areas of the design which have not yet been covered with the slurry. This may be an equilibrium phenomenon arising out of the large factor by which the concentration ofthe particles in the slurry exceeds the concentration established on the design surface when the slurry is first applied. Secondly, the plaster particles apparently penetrate deeply into the fabric fibers and even through them in traveling to the design surface. This is shown by the fact that the fibers are not visible in the surface of the finished sheet and, furthermore, if a sharp clean cut is made through the sheet to obtain a cross section, the fibers are virtually indistinguishable from the gypsum body of the sheet. Apparently, the water provides a path into and around the fibers by which the plaster particles are able to fill and occupy the most remote interior voids and open spaces in and around the fibers, resulting in a nal -sheet of high integral uniformity which possesses great strength and resiliency. I have attempted to carry out my process without wetting the fabric material and the results have been most unsatisfactory. The water path being absent, there is little penetration of fibers, the surface of the finished sheet usually contains imperfections such as air spaces, parts of the fibers are visible and the transfer of color is poor. From the foregoing it is obvious that wetting of the open mesh fabric material is a critical step in my process.

It is important to note that the function of the wet fibers of fabric materia] does not end with mere application of the gypsum plaster slurry. After the design is entirely covered with slurry, I prefer to apply pressure on the slurry as by a brush or roller to aid in causing penetration of the fibers and to ensure that every portion of the design surface is contacted by the slurry. During this time the fabric material again exerts some form of control in preventing different portions of the slurry, which by now has incorporated the major proportion of the design colors into itself, from merging into each other and thereby destroying the appearance of the design. Also, the wet fibers play an important part in the setting of the gypsum plaster. As used in the specification and claims herein, the term gypsum plaster is intended to refer to the well known class of hardenable materials which are prepared by the complete or partial dehydration of calcium sulfate dihydrate, commonly known as gypsum. Gypsum plaster is usually the hemihydrate of calcium sulfate which takes up 11/2 moles of water in permanently setting into the hard dihydrate of calcium sulfate. In providing wet fibers in my process throughout the body of the gypsum plaster while it is setting, I ensure an adequate supply of water available to the hydration reaction which is involved, so that all of the gypsum plaster is substantially converted to gypsum in a uniform manner. The reserve supply of water thus makes possible a substantially complete and uniform hydration of the gypsum plaster which leads to great strength in the final sheet.

After the gypsum plaster slurry has set to the point where it is self-supporting, the backing on which the design was first painted may be separated from the thin plaster sheet and the sheet then stored to dry completely. This may be done at ordinary room temperatures or drying may be accelerated by placing the sheet in an oven at temperatures up to about 225 F. As will be more fully explained hereinafter, the appearance of the design in the sheet will vary to a degree with the physical characteristics of the particular backing that is employed. But even through such variations the general appearance of the design is similar to a dull matte with the colors being somewhat subdued in intensity. This, of course, is often desired for purposes of interior decoration so that the sheet may be used in this form. However, I have found that the brilliance of the colors can be very substantially increased if the sheet is impregnated with a resilient plastic material capable of forming a film as by evaporation of a solvent in which it is dissolved or by coagulating from a molten state. This treatment fills all of the spaces in the porous plaster sheet and leaves a film of plastic material on the surfaces of the sheet. As a result the colors in the design be- A;` come intensely brilliant and the sheet acquires a sheen like that of marble. Also, the plastic material provides a resilient matrix in and around the rigid crystalline gypsum, which matrix readily withstands bending stresses and thus protects the fixed lattice of the gypsum from rupture. The plastic treatment also generally increases the flexural strength and resiliency of the gypsum sheet about fourfold. Since the plastic material seals the pores of the gypsum sheet, the sheet can be scrubbed with soaps, detergents or other Cleansers without any tendency of disturbing the design locked therein. While the plastic material alone may be highly fiammable, surprisingly enough once it is impregnated in the gypsum sheet it is completely non-flammable, even to the extent that it docs not char when contacted with a flame. Thus, the products of my invention are highly suitable for use in room interiors as floor tiles, wall and ceiling coverings without the danger of a fire hazard.

As to materials, the backing upon which the design is to be painted may be any flat surface which is preferably non-absorbent to water. For example, the backing may be a sheet of plastic material, a glass plate, a sheet of foam rubber, a photograph or virtually any other fiat surface. Interesting design appearances can be achieved with different backings, for example, foam rubber which gives a stippling effect while a glass plate results in an absolutely flat design surface simulating marble. Furthermore, since my process reproduces the contour of any shape or form, the backings I employ are not limited to two dimensional surfaces. I can use backings having intricate three dimensional intaglio or cameo figures therein and these will be reproduced in the gypsum sheet as corresponding cameo or intaglio gures which exactly match those of the backings. For example, I may employ wood carvings, hammered metallic plates, ornate cloth goods such as lace or tapestries, and latex sheets molded into complex three dimensional configurations as backings for the design. These shapes may be painted with a plurality of colors to produce any desired design or only discrete portions may be painted with a single color to produce a pattern contrasting with the natural white of the gypsum plaster bearing against the uncolored portions. Another backing I may use is a paraffin slab into which I incise a pattern, deposit colors upon the surfaces of the incision and then reproduce the pattern as a corresponding cameo in the gypsum sheet. If the gypsum plaster tends to adhere to a particular backing as it sets, the backing may be first coated with a separator such as sodium silicate, hydrocarbon oils or waxes, soap films and the like. However, this is not usually necessary as the gypsum plaster particles bond to each other rather than to the backing.

As to colors for the design, this may be any coloring matter which is water soluble or water dispersible. Any of the known organic dyes which have been rendered water soluble may be employed. For example, nitro, monoazo, diazo, nitroso, diphenylnaphthylmethane, triphenylmethane, xanthene, anthroquinone, azine and quinoline dyes solubilized with sulfonic, carboxyl, or hydroxyl groups are suitable. In addition, inorganic pigments which have been ground to finely divided powders and which can be dispersed in water may be used. These are usually the oxides, sulfides, chromates, ferrocyanides, or molybdates, `as well as other Werner type complexes, of various metals all of which are well known commercially available materials. As used in the specification and claims herein, the term coloring matter is intended to mean any or all of the abovementioned specific color materials as well as any other water soluble or water dispersible colors.

Either the dyes or the pigments may be used in the form of thin or heavy aqueous washes and the pigments may also be made up into thin pastes. For best results the quantity of dye or pigment should be just adequate to cover the surface of the backing without building up excessive thickness. In cases of backings such as plastic sheets where the interfacial tension between the sheet and water may make it difiicult to spread and maintain, the aqueous color in desired areas, wetting agents or organic alcohols along with a minor amount of sugar may be added to the colors to overcome any tendency toward formation of globules or droplets on the backmg.

As to the layers of fabric material, this may be any substantially open mesh fabric of various textile materials. By the term open mesh fabric material, as used in the specification and claims herein, I mean some form of fabric material in which there is a visible space or opening between the weft and warp of the fabric so that the gypsum plaster slurry can pass through the material. The material I prefer to use is cheesecloth. However, other materials such as burlap, loosely woven cotton goods, and synthetic textiles made from nylon and polyesters may also be employed. In addition porous paper sheets such as tissue paper may be substituted for the fabric materials. The number of layers of the fabric material may vary from one to about six. Generally, I prefer to use two layers which are adequate and do not unduly increase the thickness of the final gypsum sheet.

As to the plastic materials for impregnating the gypsum sheet, these may be resilient film forming organic plastics such as cellulose nitrate, cellulose acetate, cellulose butyrate, cellulose acetate butyrate, polymerized esters of acrylic and methacrylic acids, vinyl polymers and like materials. Preferably the plastic is dissolved in a solvent which is moderately volatile at ordinary room temperatures such as low molecular weight alcohols, ketones and esters including acetone, ethyl acetate and mixtures thereof and the gypsum sheet is immersed in the plastic solution until it has been thoroughly impregnated. Thereafter, the sheet, is stored to permit the solvent to evaporate, leaving behind the plastic film and matrix. The fact that the organic solvents do not attack the sensitive organic dyes in the design is further evidence for my belief that the design colors are actually incorporated or locked within the crystalline lattice of the gypsum particles. Another way to impregnate the gypsum sheet is to mix dry plastic particles into the initial gypsum plaster slurry. The plastic, being water insoluble, will be incorporated throughout the gypsum sheet in the form of particles when the sheet has set. Thereafter, the sheet is immersed in a solvent for the plastic and this will dissolve the plastic without substantially removing it from the sheet. The solvent is then permitted to evaporate, leaving behind the plastic lilm and matrix as in the first method. In this second method the amount of plastic material mixed into the slurry should be no more than about equal the volume of gypsum plaster therein, although smaller amounts may be used. I prefer to use a mixture in which the plastic material constitutes about 1/3 the total volume of the gypsum plaster and plastic material combined.

As to the physical condition of the gypsum plaster slurry at the time of contact with the coloring matter of the design, in general l prefer that the slurry be as loose and fiowable as possible in order to obtain maximum transfer of color. With certain of my techniques involving in situ work on walls or similar vertical surfaces, the slurry may necessarily have to be in a less flowable condition physically at the time of contact but this does not prevent transfer of color as long as the slurry is still in an impressionable form. By that, I mean that the slurry is still capable of receiving and retaining the contour of an obiect pressed into it and if this is so, color designs may be permanently incorporated in the final sheet of gypsum in accordance with my invention.

While the methods I have described hereinabove in' volve placing the open mesh fabric material upon the design and then applying gypsum plaster slurry thereto,

` step of preparing a mural it is also possible to first apply the slurry to the fabric material separately and then place the preformed fabric material-slurry assembly upon the design. This is done by placing the layers of fabric material upon some form of support such as a plastic film and then the fabric material is thoroughly wetted with water. The aqueous slurry of gypsum is then applied to the fabric layers until all of the fibers are impregnated and enveloped by the slurry. The plastic film is then lifted to carry the entire assembly to the design. The assembly is turned over so that the wet exposed surface of the gypsum plaster in the assembly can be placed down upon the design. Preferably, the assembly is rolled into contact with the design from one end to the other to make certain that the water soluble colors of the design will not be disturbed on the backing. After the assembly is in place, preferably a wet brush or roller is used to apply pressure upon the assembly to ensure maximum penetration of the gypsum plaster by the colors of the design. The supporting plastic film upon the assembly may be left in place while pressure is beinfr applied or if desired it may be first removed and addi tional gypsum plaster slurry applied to 'the assembly.

After the gypsum plaster, has hardened the thin sheet that has formed is removed and treated in the same manner described for the foregoing methods.

Another way to form the gypsum sheets of my invention is to place a layer of aqueous gypsum plaster slurry directly upon the design and then press the wet layers of the open mesh fabric material into the gypsum plaster layer. Care 'must be taken in using this method to avoid disturbing the position of the colors of the design when the gypsum slurry is first applied thereto. One way to apply the slurry is to hold a supply of slurry in some form of reservoir just above the design. The reservoir should have a narrow discharge opening of suiiicient width to extend across the width of the design. When the reservoir is opened and as slurry discharges therefrom, the design is moved under the nozzle starting with one end until the entire design is passed under the nozzle. During this time a substantially even layer of slurry will be applied to the entire design surface and thereafter the wet layers of fabric material can be placed directly into the slurry without the danger of disturbing the colors of the design. Preferably, after the fabric material has been placed into the initial layer of slurry, additional slurry is applied to the fabric material to make certain that every fiber thereof is penetrated and enveloped by gypsum plaster particles. When all of the gypsum plaster has hardened to the point where it is self-supporting, the thin sheet is then removed from the design and treated in the same manner as described hereinabove. With this ernbodiment of the invention, it is possible to use a layer of thin sheet material -to which the gypsum plaster is adapted to adhere in place of the open mesh fabric material. The sheet material may be cardboard, heavy kraft paper, oaktag, corrugated ber board, porous felt sheets and similar materials. The sheet material is first wetted and pressed down into the thin layer of gypsum plaster slurry as in the manner described for the open mesh fabric material. The gypsum plaster, as it sets into gypsum, will fuse to the thin sheet material and remain in place thereon.

Further details of my invention will be readily understood by reference to the accompanying drawings which illustrate preferred embodiments thereof and in which:

FIG. 1 is a plan view of an assembly for copying a multi-color design with the method of my invention.

FIG. 2 is a plan view of an assembly used in the first in plaster sections and afxing the same directly to a wall.

FlG. 3 is a plan view illustrating the second step of the method described for FIG. `2.

in FIG. l a print of a landscape painting, desired to be reproduced in a thin sheet of gypsum is indicated at It). This print is placed on a table or other work support (not shown) and then a glass plate l2 is placed over the print. Thereafter, the print is copied by painting the upper surface of the glass plate l2 with water soluble colors lill in the same colors, areas and delineations as those of the print which, of course, are clearly visible through the glass plate. When the step of copying the print has been completed, the colors that have been deposited upon 'the glass plate are permitted to dry. Next, two layers of dry cheesecloth 16 are placed over the glass plate, the dimensions of such layers being sulicient to cover all of the colors deposited on the plate and preferably extend out beyond the borders of the colored area about two or three inches. The cheesecloth layers and the colors thereunder are now wetted with water. This may be done with a brush or roller and it is important that the water be applied liberally with sufficient brush or roller strokes to ensure that all of the colors in the copied landscape are wetted. rThere is no problem in achieving complete wetting since the creepage of water along the dry cheesecloth iibers and dry surface of the landscape is readily visible. Also, as the cheesecloth layers are wetted they cling to the surface of the assembly so that small folds or wrinkles in the fabric can be readily smoothened. After the assembly lias been wetted, an aqueous slurry of gypsum plaster t8 is applied to its entire surface. The slurry should preferably be as loose as possible, that is, the maximum volume of water in which a given weight of gypsum plaster may be uniformly dispersed should be employed. The slurry is conveniently applied with a wet paint brush although other means such as rollers may also be used. The specic steps of applying the slurry which have given me best results are to first cover the entire assembly with the slurry and then stroke the surface of the slurry vigorously with a wet brush, either with additional slurry or with water alone. As the slurry is stroked, excess water therein Works its way up to the surface where it can be pushed out beyond the edges of the assembly with the brush and thereby discarded. Within minutes after the excess water has been discarded, the thin reinforced sheet formed upon the glass plate l2 will have set suciently to be self-supporting.

At this point the sheet is lifted away from the glass plate and stored until completely dry. As mentioned hereinabove7 drying may be accomplished by storage at atmospheric temperature or the sheet may be exposed to elevated temperatures in an oven. In either case the sheet being only about l/s inch thick, dries rapidly and thereafter it is impregnated with a lm forming plastic material to seal its pores and improve its strength and resiliency. This may be readily achieved by immersing the sheet in a bath containing the plastic material dissolved in a solvent, for example, cellulose acetate butyrate in acetone and methyl ethyl ketone. After the sheet is thoroughly penetrated with the solution of plastic, it is removed from the bath and stored to permit the solvent to evaporate. The nal result is a durable impervious copy of the original landscape with the colors having an appearance or great depth and brilliance in the gypsum sheet. The sheet may be framed and hung for display alone as in a painting or, if desired, it may be first mounted on a flat support for added rigidity.

FIGS. 2 and 3 illustrate steps in a process I employ for covering large areas of room interiors such as wall or ceilings with the gypsum sheets of my invention which together form a panoramic scene as in a mural. In this process the overall scene is first divided into a number of smaller sections, say about four feet square, in order that gypsum sheets corresponding to each section may be prepared by hand without undue difculties as to handling. Each of the scene sections is first copied in water soluble colors upon the` surface of a backing comprising a transparent lm of plastic such as polyvinylidene chloride. The technique of copying is virtually the same as that described for FIG. l except that the thin plastic film is substituted for the glass plate l2. These colored plastic i lms constitute so called negatives from which corresponding gypsum sheets are prepared and aliixed to the wall in mating relationship to reproduce the mural or panoramic scene.

After all of the colored plastic lm sections have been prepared, two brads Ztl are driven into the wall in spaced relationship above the area where one corner of the mural is to be alxed. A fairly heavy gauge sheet of vinyl plastic 22 is then slipped over the brads by means of holes 243 in the sheet. The corner plastic hlm section 26 bearing the colors of its portion of the mural is placed against the vinyl sheet and alixed thereto in proper alignment with the wall by means of strips of adhesive tape 28. Only the four corners of colored film section 26 need be joined to the vinyl sheet 22 for alignment purposes while the shcct is in vertical position against the wall. Thereafter, the sheet 22 is removed from the brads 20 and placed upon a rigid support 30 such as Masonite board. The remaining strips of tape 28 are applied to the film 26 and the sheet 23 in suicient number to smooth out any wrinkles or pleats that may have formed in the film. This is best achieved by applying the adhesive strip iirst to the margin of the lm 26, then pulling the strip away from the center of the film and pressing the remainder of the strip down upon the sheet 28 The lateral pull thus applied uniformly around the margins of the lm 26 will cause it to become completely smooth and hat.

Now, the film 26 is covered with two layers of dry cheesecloth lo, wetted with water and an aqueous slurry of gypsum plaster slurry 18 is applied to the assembly in the manner described for FG. l. lt will be noted that in this case the dimensions of the cheescloth layers are such that the layers overlap the edges of the vinyl sheet 22. This provides a temporary lock between the vinyl sheet and the gypsum plaster sheet so that when the assembly is lifted into vertical position there will be no slippage between the two. As soon as the gypsum plaster upon the lm 26 has set to the point where it is self-supporting the thin sheet Which has been consequently formed is alxed to the portion of the wall surface to which it was previously registered by means of the vinyl sheet 22 and brads 20. Aflxing the sheet to the wall is very simply done by tilting the board 30 into a vertical position, while holding the bottom edges of the board and gypsum plaster sheet together, and then hanging the vinyl sheet from the brads 2i) by means of holes 24. The board may now be discarded and then pressure is applied to the face of the vinyl sheet with a brush or roller to cause the gypsum plaster sheet behind it to adhere to the wall. Preferably, before the sheet is so affixed, the wall is iirst wetted with water or a thin coating of aqueous gypsum plaster slurry in order to increase adhesion although this is not actually necessary. At this point the gypsum plaster sheet will be firmly adhered to the wall though not permanently since the gypsum plaster has not yet dried and set completely. The vinyl sheet 22, is now separated from adhesive strips 23 and removed from the brads 20. Then the excess of the gypsum sheet extending out beyond the edges of the copied section of the mural is trimmed with a cutting tool and peeled away from the wall. Naturally, this should be done before the gypsum plaster has dried completely as separation at that time will be quite difficult.

As shown in FIG. 3, after the trimming step, the rst section of the mural reproduced in a thin gypsum sheet 32, will be in correct position against the wall since the lm 26, serving as its negative, was registered with the vinyl sheet 22 which in turn was held in a xed position by the brads 20. Also, as shown in the upper right hand corner of the first mural section, the lilm 26 is still in place against the face of the gypsum sheet 32. This is the preferred procedure both `for purposes of protecting the completed mural sections as the work progresses and for purposes of mating each mural section to an adjoining section as will be more fully described hereinbelow.

i or similar temporary means.

The second mural section is now copied and reproduced in a sheet of gypsum plaster in the same way as had been described for the first section. Wherever an edge of the second section is to mate with the first section a margin of overlap is provided in the plastic film that is to be used as a negative for the second section, that is the edge of the plastic film extends about one inch into an adjoining area of the mural already reproduced in the first plaster sheet. As a result, the overlapping margain of the plastic film, after being painted with the water soluble colors, will contain images which duplicate those appearing in about a one inch band along an edge of the first section which is to mate with an adjoining edge of the second section. In FIG. 3 the overlapping margin appears between the lines 34 and 36, line 34 being the upper edge of the plastic film used for preparing the second plaster sheet and line 36 being the lower edge of the first gypsum sheet 32 already affixed to the Wall.

The overlapping margins along adjoining edges of the mural sections provide a simple means for mating each section with its surrounding sections in perfect alignment and continuity. Thus, as shown in FIG. 3, when the second gypsum plaster sheet is afiixed to the wall minor adjustments in its position may be made along the overlapping margin without affecting the continuity of that portion of the mural depicted in these two sections. Furthermore, the overlapping portion of the gypsum plaster sheet of the second section does not adhere to the first sheet since the plastic film 26 is still in place against the face of the first sheet and thus provides a water impervious barrier between the two sheets. After the second sheet has been aflixed to the wall in the aligned position the vinyl sheet 22 is removed and the free edges of the gypsum plaster sheet are trimmed away as previously described hereinabove. Then the sheet is cut along a line overlying 36 and the excess overlapping margin of the sheet is discarded. The remaining upper edge can now be pressed flush with the lower edge of the first sheet 32 to give a continuous image across the line of abutment between the two edges.

The remaining sections of the mural are reproduced in gypsum plaster sheets and mounted upon the wall in like manner until the mural has been completed. Thereafter, the plastic films upon the face of the mural are removed if they have not already separated from the mural of their own accord. The plastic films are only very weakly held against the gypsum plaster sheets under `the influence of aqueous surface tension or static electric charges and in some instances, when the gypsum plaster has dried completely, the films will separate as a natural consequence. At any rate, the films are very readily removed from the completed mural merely by pulling them away. Thereafter, the mural is impregnated with a solution of thermoplastic material to develop brilliancy of colors and seal the pores of the gypsum sheets. The plastic solution may be applied with a brush or roller and after the solvent has evaporated the mural will have a highly attractive marbleized appearance.

A variation in my process of preparing mural type i decorations is to first copy the entire mural with water soluble colors upon a single sheet of thin plastic film. When the colors have dried this lm may be rolled up upon a lightweight core such as a cardboard cylinder. Then, I cover the wall which is to support the mural with two layers of open mesh fabric material such as cheesecloth. This may be done by attaching the upper edges of the fabric layers to the wall with adhesive tape, tacks, Thereafter, the fabric layers and the wall are thoroughly wetted with water. This wall cause the fabric layers to cling to the wall and any folds or wrinkles therein can be readily smoothed out. Next, an aqueous slurry of gypsum plaster is applied to the fabric layers with a brush or roller in sufficient amount to envelop and penetrate every fiber of the fabric with gypsum plaster. Immediately thereafter, the plastic l@ film bearing the colors and image of the mural is unrolled and simultaneously applied to the plaster-fabric material assembly, the colored side of the film being, of course, placed in contact with the surface of the assembly. Preferably, pressure is applied to the film with a wet brush or roller to make certain that all of the colors on the opposite side are brought into Contact with the gypsum plaster-fabric assembly. If any air bubbles should become entrapped under the film, one or two pinholes may be punched into the film to vent the air without any dimculty. After the colors upon the film have been incorporated in the gypsum plaster sheet, any excess portions of the sheet around the borders of the mural which have not received color are trimmed and removed from the wall. The plastic film may then be left in place against the plaster sheet or, if desired, removed while the sheet dries completely. The dried gypsum sheet is finally treated with a solution of plastic material as described hereinabove.

While I have now described various ways to reproduce multi-colored scenes, it is obvious that my process may also be used in connection with a single color which is deposited upon a backing in a specific form or pattern which contrasts with the natural white of the gypsum plaster. Sheets of smaller uniform size may also be prepared in multior single color designs and affixed to floors like conventional tiles to provide highly attractive ioor coverings. In the process described in connection with FIGS. 2 and 3 I can prepare all of the mural sections beforehand and then affix them to a wall with conventional adhesives instead of registering and mounting each section as it is prepared. Other variations of my processes will be obvious to those skilled in the art.

As mentioned hereinabove the appearance of a design in the gypsum plaster sheet will depend on the physical characteristics of the backing upon which the design is first painted. I have described my process in connection with backings comprising a thin plastic film and a glass plate. However, almost any object or material can serve as a backing. For example, I can use a photograph, or a blotter or a painting on paper. In the case of the photograph best results are achieved by placing tissue paper over the photograph and by painting the design on the tissue paper. When the design is subsequently reproduced with layers of wet cheesecloth and the aqueous slurry of gypsum plaster the tissue paper becomes an integral part of the hardened plaster sheet without detracting in any way from the appearance of the design in the final sheet.

In another embodiment of my invention I use a modified silk screen technique to produce multi-color designs in a gypsum sheet. In this process I prepare a plurality of rigid screens of mesh material such as silk or nylon by mounting the borders of the mesh material in Wood frames. Each screen is then placed over a design that is desired to be reproduced and areas of the screen are coated with melted parafiin. The area of each screen which remains uncoated will correspond to an area of the design which is desired to be reproduced with a particular color. Thus, the number of screens that are employed will depend on the complexity of the design and the number of colors to be used in the reproduction.

After the screens have been treated with paraflin, I then prepare a thin sheet of gypsum plaster or any flat surface such as a table, sheets of plastic material, or a glass plate. The plaster sheet is prepared by placing from one to six layers of wet cheesecloth on the flat surface and then applying an aqueous slurry of gypsum plaster in the manner previously described. Then, while the plaster sheet is still wet, the first of the paraffin coated screens is placed over the plaster sheet and a colored aqueous slurry of gypsum plaster which has been previously prepared by dispersing the gypsum plaster in an aqueous solution of a water soluble dye, is applied to the screen. The colored plaster slurry passes through the open areas of the screen and merges with the surface of the thin white plaster sheet underneath. The screen is then removed frorn the surface of the plaster sheet and the second screen is placed thereon. To this screen is then applied another colored aqueous slurry of gypsum plaster having a different color than the first. This colored plaster slurry passes through the open areas of the second screen to merge with uncolored areas of the surface of the white plaster sheet. The above procedure is repeated with the remaining screens until the final multi-color design has been reproduced in the surface of the gypsum plaster sheet. Thereafter, the gypsum plaster sheet is thoroughly dried and treated with the solution of plastic material as described hereinabove. The appearance of the hnished sheet is quite unique in that each of the colored areas may be at different surface levels.

In another embodiment utilizing the modified silk screen technique I coat the surface of a glass plate with a separator such as sodium silicate or oil or just clean the glass and leave it uncoated. Then, I deposit colored aqueous slurries of gypsum plaster on the plate through successive silk screens, the number of screens being selected according to the complexity of the design that is desired. After all of the colored slurries have been deposit-ed on the plate I then place from one to six layers of wet cheesecloth over the colored slurries. Then I apply an aqueous slurry of white gypsum plaster to the wet cheesecloth and spread it back and forth with a brush or roller until every fiber of the cheesecloth is penetrated and enveloped by the gypsum plaster. particles. During this process the colored slurries of plaster will fuse with the white plaster slurry and when the entire assembly has set sufficiently to be self-supporting it may be lifted from the glass plate. Thereafter, the entire assembly is thoroughly dried and treated with the solution of plastic material as described hereinabove. The design made with this technique will be completely flat and uniform throughout since it is always in contact with the glass plate during the processing steps.

Another way to use my process in connection with the modified silk screen technique is to place about three layers of wet open mesh fabric material on a flat smooth backing such as a glass plate. Then the layers of fabric material are painted with an aqueous slurry of gypsum plaster to form a thin sheet. A plurality of screens are then coated with paraffin as previously described hereinabove. Then, each screen is placed on the sheet of gypsum plaster and an aqueous solution of a water soluble dye is passed through the open area of the screen. During this process the water soluble dye penetrates into the sheet of wet gypsum plaster. When the last screen has been painted with aqueous dye material the plaster sheet is thoroughly dried and treated with a solution of plastic material as described hereinabove. With this process it is difficult to prevent merging of colors along the lines where two different colors meet in the design. Therefore, I do not recommend this process where exact reproduction of a design is desired. However, where exact fidelity of a design is not necessary this technique can be used with great advantage to prepare modern decorative covering materials where an abstract arrangement of colors is relied on for the decorative effect.

It will be seen that with the modified silk screen technique my invention is capable of many variations and is adapted to produce all kinds of designs and effects. For example, the number of screens can be varied to more or less than the number of different colors appearing in the design to be reproduced and the order in which the screens are placed over the plaster sheet can be varied to produce many different designs and effects.

In another embodiment utilizing the silk screens, I coat the surface of a glass plate with a separator as described hereinabove. Then I deposit colored slurries of gypsum plaster on the plate through a plurality of silk screens. After all of the colored slurries have been deposited on the glass plate, I then place over the slurry a sheet of thin material to which the gypsum plaster will adhere. The material can be a sheet of cardboard, heavy kraft paper, oaktag, corrugated fiber board and similar rnaterials. The colored slurries of plaster will fuse to the thin sheet of material which serves as a support for the gypsum plaster layer. Thereafter, the entire assembly can be affixed to walls or ceilings in conventional manner. The support material provides an excellent base to which conventional adhesives can be applied for readily mounting the decorative covering material to a wall or ceiling. It will be understood that the other described methods for reproducing designs in the thin sheet may be employed without using any fabric material provided the gypsum plaster sheet is anchored to a support as described hereinabove.

It will ne understood that it is intended to cover all changes and modifications of the preferred embodiments of the invention herein chosen for the purpose of illustration which do not depart from the spirit and scope of the invention.

What I claim:

1. A method of forming color designs in gypsum sheets which comprises the steps of depositing coloring matter in a substantially aqueous vehicle upon a backing to form a design thereon, said backing being separate and distinct from hereinafter-specified open mesh fabric material, permitting the coloring matter to dry, placing at least one layer of open mesh fabric material against the coloring matter, wetting the fabric material and the coloring matter with water, causing contact between the coloring matter and an aqueous slurry of gypsum plaster and simultaneously impregnating and enveloping the fabric material with said slurry at any time prior to when the gypsum plaster is incapable of receiving a physical impression, and then permitting the gypsum plaster to harden whereby the design is incorporated therein.

2. The method in accordance with claim ll which incudes the steps of drying the hardened gypsum plaster and then impregnating it with a resilient film-forming plastic material.

3. A method of forming color designs in gypsum sheets which comprises the steps of coating different portions of a plurality of rigid open meshed screens with a solid water-impervious material so that in each case less than the total area of the open mesh of each screen is covered with said water-impervious material placing at least one layer of open mesh fabric material on a backing, wetting the fabric material and the backing with water, impregnating and enveloping the fabric material with an aqueous slurry of gypsum plaster, placing the first of the plurality of screens upon the gypsum plaster, passing an aqueous slurry of gypsum plaster having coloring matter therein through the uncoated open mesh of the screen to merge with the gypsum plaster thereunder, removing the screen, repeating the two last mentioned steps in succession with each of the remainder of the plurality of screens,

'each screen having passed through its uncoated open mesh an aqueous slurry of gypsum plaster having different coloring matter from that for any other screen, and then allowing all of the gypsum plaster to harden whereby a design is incorporated therein.

4. A method of forming color designs in gypsum sheets which comprises the steps of depositing coloring matter in a substantially aqueous vehicle upon a backing to form a design thereon, said backing being separate and distinct from hereinafter-specified open mesh fabric material, permitting the coloring matter to dry, wetting at least one layer of open mesh fabric material with water, impregnating and enveloping said open mesh fabric material with an aqueous slurry of gypsum plaster, causing contact between the coloring matter and the gypsum plaster at any time prior to when the gypsum plaster is incapable of receiving a physical impression, and then permitting the gypsum plaster to harden whereby the design is incorporated therein.

S. A method of forming color designs in gypsum sheets which comprises the steps of depositing coloring matter in a substantially aqueous Vehicle upon a backing to form a design thereon, said backing being separate and distinct from hereinafter-specified open mesh fabric material, permitting the coloring matter to dry, wetting at least one layer of open mesh fabric material with water, impregnating and enveloping said open mesh fabric material with an aqueous slurry of gypsum plaster, causing contact between the coloring matter at any time prior to when the gypsum plaster is incapable of receiving a physical impression, placing a layer of porous sheet material upon the gypsum plaster to which sheet material the gypsum plaster is adapted to adhere, and permitting the gypsum plaster to harden whereby the design is incorporated therein.

1 4 References Cited by the Examiner UNITED STATES PATENTS 99,479 2/70 Robbins 18-61 283,057 8/83 Aldrich 41--26 451,799 5/91 Bleiss 18-61 1,366,754 1/21 Torno 18--61 1,474,817 11/23 Fincke. 1,526,928 2/25 Owens. 1,641,404 9/27 Washington 18-61 2,193,635 3/40 Marshall 1861 X 2,416,997 3/47 Hewitt 41-26 ROBERT F. WHITE, Primary Examiner.

WILLIAM J. STEPHENSON, ALEXANDER H. BROD- MERKEL, Examiners. 

1. A METHOD OF FORMING COLOR DESIGNS IN GYPSUM SHEETS WHICH COMPRISES THE STEPS OF DEPOSITING COLORING MATTER IN A SUBSTANTIALLY AQUEOUS VEHICLE UPON A BACKING TO FORM A DESIGN THEREON, SAID BACKING BEING SEPARATE AND DISTINCT FROM HEREINAFTER-SPECIFIED OPEN MESH FABRIC MATERIAL, PERMITTING THE COLORING MATTER TO DRY, PLACING AT LEAST ONE LAYER OF OPEN MESH FABRIC MATERIAL AGAINST THE COLORING MATTER, WETTING THE GABRIC MATERIAL AND THE COLORING MATTER WITH WATER, CAUSING CONTACT BETWEEN THE COLORING MATTER AND AN AQUEOUS SLURRY OF GYPSUM PLASTER AND SIMULTANEOUSLY IMPREGNATING AND ENVELOPING THE FABRIC MATERIAL WITH SAID SLURRY AT ANY TIME PRIOR TO WHEN THE GYPSUM PLASTER IS INCAPABLE OF RECEIVING A PHYSICAL IMPRESSION, AND THEN PERMITTING THE GYPSUM PLASTER TO HARDEN WHEREBY THE DESIGN IS INCORPORATED THEREIN.
 4. A METHOD OF FORMING COILOR DESIGNS IN GYPSUM SHEETS WHICH COMPRISES THE STEPS OF DEPOSITING COLORING MATTER IN A SUBSTANTIALLY AQUEOUS VEHICLE UPON A BACKING TO FORM A DESIGN THEREON, SAID BACKIANG BEING SEPARATE AND DISTINCT FROM HEREINAFTER-SPECIFIED OPEN MESH FABRIC MATERIAL, PERMITTING THE COLORING MATTER TO DRY, WETTING AT LEAST ONE LAYER OF OPEN MESH FABRIC MATERIAL WITH WATER, IMPREGNATING AND ENVELOPING SAID OPEN MESH FABRIC MATERIAL WITH AN AQUEOUS SLURRY OF GYPSUM PLASTER, CAUSING CONTACT BETWEEN THE COLORING MATTER AND THE GYPSUM PLASTER AT ANY TIME PRIOR TO WHEN THE GYPSUM PLASTER IS INCAPABLE OF RECEIVING A PHYSICAL IMPRESSION, AND THEN PERMITTING THE GYPSUM PLASTER TO HARDEN WHEREBY THE DESIGN IS INCORPORATED THEREIN. 